Install NPM into home directory with distribution nodejs package (Ubuntu)

I'd like to use the distribution Node.js packages (or the chris-lea ppa for more recent releases) but install NPM to my home directory.

This may seem picky, but it's a pretty idiomatic way for polyglot/github-using developers to setup language runtime/library environments under Linux: distro packages for the runtime, 3rd-party libraries in per-user environment (see virtualenv, RVM - RVM will also build Ruby for you if you want). If necessary I will build node locally but it's a PITA since Node is becoming an incidental development requirement for lots of projects.